Читать книгу Illustrations of the Croton Aqueduct - F. B. Tower - Страница 8

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This is probably one of the most ancient Aqueducts constructed, out of Rome, by the Romans. It is attributed to Agrippa, son-in-law of Augustus, to whom that emperor gave the government of the country becoming a Roman Colony.

Agrippa, flattered by the honors which he received from the inhabitants of Nismes, made his residence there: he enclosed the town with new walls, built baths, and probably the Aqueduct of the bridge of Gard (“pont du Gard”) for bringing water to them.

This Aqueduct is nearly thirty miles in length, forming, in its course, the figure of a horse-shoe. It brought water from the fountains of Eura and Airan, situated in the neighborhood of the town of Uzès. The bridge of Gard was about the middle part of the work, and the Aqueduct terminated at Nismes.

This Aqueduct traversed a very mountainous country, piercing through mountains and crossing valleys by means of arches upon arches, forming magnificent structures entirely of cut stone. The Aqueduct or channel-way is formed of stone throughout the whole length. The bottom of the interior has a curved form, being an arc of a circle; the sides are vertical, and the top covered with a flagging of cut stone, except where it is under ground, in which situation the top is covered by an arch of stone. The interior face of the walls and the bottom were covered with a coat of plastering two inches in thickness, composed of quick-lime, fine sand, and brick nearly pulverized. This coating has now a tenacity and consistence equal to the hardest stone.

The size of the channel-way is the following: 4 feet wide and 5⅓ feet high, except where the top is covered with an arch, in which case it is 7½ feet high in the interior.

The descent of the Aqueduct is 1 foot in 2500 feet, or 2-11/100 feet per mile.

The water which flowed in this Aqueduct formed a deposit upon the sides, of lime, until nearly half the channel was closed; this deposit amounting to a thickness of 11 inches on each side. By the height of this deposit it has been ascertained that the water flowed generally with a depth of 3¼ feet.

The pont du Gard is that part of the Aqueduct of Nismes which crosses the deep valley in which runs the Gardon or Gard. This part, considered alone, is one of the noblest monuments built by the Romans among the Gauls. It is composed of three ranges of arches one above another. The first range, under which the Gardon flows, is formed by 6 arches; the second by 11, and the third by 35, all of which are semicircular; supported upon piers of greater or less height.

The channel in which the water flows is upon the top of the third range of arches, and is 160 feet above the water of the river. The whole length of this bridge is about 900 feet.

The bridge of Gard having been broken down at the two extremities, at a period very remote and uncertain, it is thought that this destruction may be attributed to the Barbarians who invaded the country of Nismes a short time after their first invasion, which is fixed at the commencement of the fifth century, about the year 406, and it is supposed that by this means they would deprive the inhabitants of Nismes of the water furnished by the Aqueduct, and force them to yield. But by this supposition, which is very probable, the water had been running in this Aqueduct for more than four centuries; and this structure which has been out of use during fourteen hundred years, is still in such a state of preservation that it could be restored without a very great expenditure of money.